HOUGHTON – It’s a good thing the Ranger III isn’t on the National Park Service payroll, because figuring out the job descriptions would make all kinds of trouble for accounting.

“She’s a package freighter, passenger ship, tank ship and crane ship,” said Captain Bill Hanrahan, who’s in his 22nd season piloting the Ranger III from Houghton to Isle Royale and back, carrying passengers, park service personnel and all the supplies that keep the island operating.

At times, the Ranger has even served as a light icebreaker, said Hanrahan. The ship is in its 57th season serving Isle Royale, on her second pair of engines, and for now, it’s still going strong.

“There is talk of a Ranger IV,” said Hanrahan. “The Ranger III is of an age when you start talking about a replacement. … In its current configuration, it can probably operate another 15 years.”

On Thursday, Hanrahan piloted guests on a voyage through the Ranger III’s history, all without leaving the National Park Service dock on the Houghton waterfront. About a dozen guests joined him aboard the ship to hear his presentation “Ranger III: Isle Royale’s Ship of All Trades.”

“I think the ship is much more complex than I understood, and bigger than I imagined,” said Tom Crane of Davenport, Iowa. “I was very impressed with the captain and the ship.”

Crane said he and his wife, Jo Ann, might not be planning any upcoming trips to the island – they’d hiked the Greenstone Ridge about 20 years ago – but they still made it a point to climb aboard for a Ranger III canal cruise when they had the chance.

Hanrahan said the Ranger III was authorized by Congress as part of Mission ’56, a program to fund national parks infrastructure marking the 50th anniversary of the national parks system. The boat was built in 1958 by Christy Shipbuilding in Sturgeon Bay, Wisconsin, at a cost of about $1.1 million. While the company has changed, the Ranger has returned to the same Lake Michigan boatyard for maintenance and refits ever since.

While most people think of the Ranger as a passenger ship, he said, it’s officially considered a package freighter, and also inspected as a tank ship. The Ranger carries the vast majority of supplies for park service staff on the island as well as its tourist concessions, and also hauls the diesel fuel to power the island’s electric generators.

“Few people know this, but it’s the only tank ship owned by federal government in commerce,” Hanrahan noted, adding it’s also the only U.S. tanker allowed to operate without a double hull. Post-Exxon Valdez regulations required all tankers be double-hulled by 2015, he said, but former Senator Carl Levin convinced Congress that an unusual tank configuration meant risk would have actually increased if the Ranger III had complied with the regulations.

As a cargo ship, he said, the Ranger III hauls about 12 to 14 tons of cargo each season, about 40 percent of which requires a crane. Its most unusual cargo may have been when it hauled a seaplane home from Isle Royale after the plane burned out a piston and made an emergency landing on Rock Harbor.

Normally, Hanrahan said, the biggest challenges have to do with weather. He’s run the boat in up to 14-foot waves, he said, when forecasts suggested the lake wouldn’t be quite so dicey.

“To be truthful, I’ve gotten sick myself, several times,” he admitted. “I always defend myself by saying Horatio (Nelson), head of the British Navy and possibly the most spectacular sailor of all time, got sick all the time.”

In recent years, he said, the Ranger has had to battle ice, both opening up the island and crossing Superior in early spring after returning from dry dock and a hull repainting.

In 2014, “we came through heavy ice when we came back in May, and didn’t come out of the ice until Eagle Harbor,” he said. “I thought for sure the paint was going to be off the bow and stem. We got here, no paint missing.”

Hanrahan is the Ranger’s longest serving captain, and it looks like the ship will outlast him as well. Either this season or next will likely be his last at the helm, he said, though it’s obvious parting won’t be easy.

“It’s a great boat,” he said. “The engineering, the stoutness. It’s been in heavy weather, and it holds up.”